In the semiconductor industry, there are a number of different techniques that are used in the fabrication and packaging of integrated circuit devices. Although techniques vary extensively, most semiconductor devices have a number of bond pads on their top surface that serve as input/output (I/O) pads. The geometry of the bond pads is generally not considered critical, but the most common bond pad geometry is substantially square. A variety of different materials are used to form the bond pads, with one common material being aluminum. As is well known in the art, aluminum bond pads are somewhat prone to corrosion, especially if moisture penetrates to the bond pad.
During packaging of integrated circuits, the bond pads are typically electrically coupled to other components to facilitate connection to other integrated circuits or external devices. At the present time, wire bonding remains the dominant chip interconnection technology. In wire bonding, one end of a very fine wire is typically ultrasonically or thermosonically bonded to a bond pad and the other end is ultrasonically/thermosonically bonded to the component that the bond pad is to be electrically connected to (as for example a lead frame lead or a substrate trace). Generally the first end of the bonding wire is ball bonded to the bond pad using a wire bonding machine having a capillary that carries the bonding wire. During the ball bonding, it is generally considered important (if not imperative) that the capillary and thus the ball bond not contact the semiconductor passivation that surrounds the bond pad to avoid damaging the semiconductor device itself. Thus a portion of the bond pad remains exposed after wire bonding and the exposed portion of the bond pad is potentially subject to corrosion.
Currently, a number of techniques have been developed to seal or otherwise protect the bond pads from corrosion. However, there are always ongoing efforts to reduce the costs and improve the quality of packaging of semiconductor products. Accordingly improved techniques for sealing bond pads from corrosion would be desirable.